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Improve the font rendering demo

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Show the pixel grid, extents, and baseline.
This commit is contained in:
Matthias Clasen 2019-07-25 18:49:00 -04:00
parent 4427bde8a7
commit 0820a79bf5
1 changed files with 54 additions and 6 deletions
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60
demos/gtk-demo/fontrendering.c
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@ -32,6 +32,7 @@ update_image (void)
PangoFontDescription *desc;
PangoLayout *layout;
PangoRectangle ink, logical;
int baseline;
cairo_surface_t *surface;
cairo_t *cr;
GdkPixbuf *pixbuf;
@ -40,6 +41,7 @@ update_image (void)
cairo_font_options_t *fopt;
cairo_hint_style_t hintstyle;
cairo_hint_metrics_t hintmetrics;
int i;
if (!context)
context = gtk_widget_create_pango_context (image);
@ -77,19 +79,64 @@ update_image (void)
pango_layout_set_font_description (layout, desc);
pango_layout_set_text (layout, text, -1);
pango_layout_get_extents (layout, &ink, &logical);
baseline = pango_layout_get_baseline (layout);
pango_extents_to_pixels (&logical, NULL);
pango_extents_to_pixels (&ink, NULL);
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, logical.width, logical.height);
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, ink.width + 20, ink.height + 20);
cr = cairo_create (surface);
cairo_set_source_rgb (cr, 1, 1, 1);
cairo_paint (cr);
cairo_set_source_rgb (cr, 0, 0, 0);
cairo_move_to (cr, 10, 10);
pango_cairo_show_layout (cr, layout);
cairo_destroy (cr);
g_object_unref (layout);
pixbuf = gdk_pixbuf_get_from_surface (surface, 0, 0, cairo_image_surface_get_width (surface), cairo_image_surface_get_height (surface));
pixbuf2 = gdk_pixbuf_scale_simple (pixbuf, gdk_pixbuf_get_width (pixbuf) * scale, gdk_pixbuf_get_height (pixbuf) * scale, GDK_INTERP_NEAREST);
g_object_unref (pixbuf);
cairo_surface_destroy (surface);
surface = cairo_image_surface_create_for_data (gdk_pixbuf_get_pixels (pixbuf2),
CAIRO_FORMAT_ARGB32,
gdk_pixbuf_get_width (pixbuf2),
gdk_pixbuf_get_height (pixbuf2),
gdk_pixbuf_get_rowstride (pixbuf2));
cr = cairo_create (surface);
cairo_set_line_width (cr, 1);
cairo_set_source_rgba (cr, 0.2, 0, 0, 0.2);
for (i = 1; i < ink.height + 20; i++)
{
cairo_move_to (cr, 0, scale * i - 0.5);
cairo_line_to (cr, scale * (ink.width + 20), scale * i - 0.5);
cairo_stroke (cr);
}
for (i = 1; i < ink.width + 20; i++)
{
cairo_move_to (cr, scale * i - 0.5, 0);
cairo_line_to (cr, scale * i - 0.5, scale * (ink.height + 20));
cairo_stroke (cr);
}
cairo_set_source_rgba (cr, 0, 0, 1, 1);
cairo_rectangle (cr,
scale * (10 + (double)logical.x / PANGO_SCALE) - 0.5,
scale * (10 + (double)logical.y / PANGO_SCALE) - 0.5,
scale * ((double)logical.width / PANGO_SCALE) + 1,
scale * ((double)logical.height / PANGO_SCALE) + 1);
cairo_stroke (cr);
cairo_move_to (cr, scale * (10 + (double)logical.x / PANGO_SCALE) - 0.5,
scale * (10 + baseline / PANGO_SCALE) - 0.5);
cairo_line_to (cr, scale * (10 + (double)(logical.x + logical.width) / PANGO_SCALE) + 1,
scale * (10 + baseline / PANGO_SCALE) - 0.5);
cairo_stroke (cr);
cairo_surface_destroy (surface);
}
else
{
@ -135,17 +182,18 @@ update_image (void)
cairo_destroy (cr);
pango_layout_iter_free (iter);
g_object_unref (layout);
pixbuf = gdk_pixbuf_get_from_surface (surface, 0, 0, cairo_image_surface_get_width (surface), cairo_image_surface_get_height (surface));
pixbuf2 = gdk_pixbuf_scale_simple (pixbuf, gdk_pixbuf_get_width (pixbuf) * scale, gdk_pixbuf_get_height (pixbuf) * scale, GDK_INTERP_NEAREST);
g_object_unref (pixbuf);
cairo_surface_destroy (surface);
}
pixbuf = gdk_pixbuf_get_from_surface (surface, 0, 0, cairo_image_surface_get_width (surface), cairo_image_surface_get_height (surface));
pixbuf2 = gdk_pixbuf_scale_simple (pixbuf, gdk_pixbuf_get_width (pixbuf) * scale, gdk_pixbuf_get_height (pixbuf) * scale, GDK_INTERP_NEAREST);
gtk_picture_set_pixbuf (GTK_PICTURE (image), pixbuf2);
g_object_unref (pixbuf);
g_object_unref (pixbuf2);
cairo_surface_destroy (surface);
pango_font_description_free (desc);
}